(CNN) -- FIFA's ethics committee is scheduled Sunday to question two men, including a former challenger to incumbent Sepp Blatter for control of the international football association, about bribery allegations against them.

Mohamed bin Hammam bowed out of the race for FIFA president early Sunday, hours before the start of the ethics hearing. Jack Warner, who runs the CONCACAF federation covering Central and North America, is also scheduled to face questions from the ethics panel about the bribery allegations.

Bin Hammam announced his decision to quit the race on his blog, seemingly clearing the way for the 75-year-old Blatter to retain the position he's held as head of world football's governing body since 1998. The election is set for June 1.

"I set out my goals and ambitions clearly to further the cause of democracy within FIFA through a commitment to transparency and accountability," said bin Hammam, the head of the Asian Football Confederation. "In addition to this, I wanted to spark a debate about change in FIFA.

"However, recent events have left me hurt and disappointed -- on a professional and personal level," he added. "I cannot allow the (game) that I loved to be dragged more and more through the mud, because of competition between two individuals."

FIFA executive committee member Chuck Blazer has accused bin Hammam and Warner of bribery related to a meeting they held with the Caribbean Football Union on May 10 and 11.

Bin Hammam has denied any wrongdoing, claiming the allegations are all part of a conspiracy to discredit his bid to become FIFA president. Blatter, a Swiss national, wrote in his column for Inside World Football that he feels it is "ludicrous and completely reprehensible" to suggest he is behind the investigation.

Last Thursday, bin Hammam demanded that Blatter also be included in the probe, after claiming the FIFA president was also named in evidence handed to the ethics committee. FIFA confirmed on Friday that Blatter had a case to answer and would take questions at Sunday's ethics committee hearing.

In a statement, the sports association said bin Hammam claimed that Warner, a FIFA vice president, would have told Blatter in advance about alleged cash payments to delegations attending the Caribbean Football Union meeting, and that he "would have had no issue with these."

Again asserting his innocence, bin Hammam said Sunday he hoped his decision to pull out of the presidential race would not be tied to the probe.

"I will appear before the ethics committee to clear my name from the baseless allegations that have been made against me," he wrote, while also singling out Warner for thanks. "I promise those who stood by me that I will walk with my head high, and will continue to fight for the good of the game."

The Qatari man vowed to also fight "to restore FIFA's reputation to what it should be -- a protector of the game that has credibility through honesty, transparency and accountability." And he said he believed his presidential run helped further that cause.

"I believe my candidacy has been a catalyst for debate within FIFA and has brought change to the top of the agenda," bin Hammam said.